Investigate the relationship between sound pressure level (SPL) and signal amplitude.
Sound Pressure Level & Amplitude Aim Investigate the relationship between sound pressure level (SPL) and signal amplitude. Summery I constructed the apparatus as shown below and collected results. The results do not show what I expected and do not adhere to the rules and physical theory I have researched. The investigation has not shown what I had intended it to but I can suggest several reasons as to why. NB: Large copies of all the graphs used are included at the end of the document Planning As a sound engineer I have wondered for some time as to the relationship between increases in power output of a sound system and changes in sound pressure level (SPL). It seems to me that there is not a direct relationship between the two. I plan to simplify the idea of a sound system into a signal generator/amplifier and a single speaker. The SPL will be measured using a sound pressure level meter (Figure 2). Variables and constants; the SPL meter will be placed a fixed distance away from the speaker, the frequency emitted from the speaker with remain constant, the amplitude of the signal will be varied to change the power output of the speaker. Figure 1 ? Figure 2 ? SPL meter as it was used in the application I performed some preliminary experiments to determine: * The distance between the SPL meter and the speaker. * The frequency of the signal the speaker should
Is there any rule governing the angle light is refracted through?
Is there any rule governing the angle light is refracted through? Aim: To find a connection or rule governing that angle light is refracted through. Introduction: Visible light is s form of energy that we can detect with our eyes. Light moves in waves. The light that we can see has a wavelength of about 1/2000 of a millimetre. The speed of light in air is 300 million metres per second. This is about a million times faster than the speed of sound. Light travels more slowly in glass than it does in air. It goes about two-thirds as fast through glass than it does in air. This is the reason why light is refracted. Since the light is being slowed down by the optically more dense medium, the ray of light travelling from the air into the glass will bend towards the normal. As below: A number called the refractive index measures how quickly light travels through a certain material. To work this out you would need this following equation: Refractive Index of a substance = Speed of light in air Speed of light in the substance The refractive index of glass and Perspex is 1.5. The greater the number, the slower light passes through the substance. Here are some other refractive indexes for other materials: Substance Refractive Index Speed of light Air 1.0 300,000,000 Water 1.33 225,000,000 Perspex 1.5 200,000,000 Glass 1.5 200,000,000
The Origins & Evolution of Sampling and Synthesis
Sampling & Synthesis Section One Section Two The Origins & Evolution of Sampling and Synthesis A synthesizer, built especially for sound production or "synthesis" and modification, is essentially a device that merges sound generators and sound modifiers in one package with an integrated control system. The first and most elaborate of these devices was the RCA Electronic Music Synthesizer, first exposed in 1955. But the story goes back far before that. Radio engineers experimenting with radio vacuum tubes discovered the principles of beat frequency or heterodyning oscillators by chance during the first decades of the twentieth century. The heterodyning effect is created by two high radio frequency sound waves of similar but varying frequency combining and creating a lower audible frequency, equal to the difference between the two radio frequencies. The musical potential of the effect was noted by several engineers and designers including Maurice Martenot, Nikolay Obukhov, Armand Givelet and Leon (or Lev) Sergeivitch Termen the Russian Cellist and electronic engineer. One problem with utilizing the heterodyning effect for musical purposes was that as the body came near the vacuum tubes the capacitance of the body caused variations in frequency. Leon Termen realized that rather than being a problem, body capacitance could be used as a control mechanism for an instrument
Investigation into the Strength of an Electromagnet
George Maund Investigation into the Strength of an Electromagnet Planning Experimental Procedure When electric current is passed through a wire a magnetic field is created. If you wind the wire around an iron core, then you have an electromagnet. They have North and South poles just like normal magnets, but it does have some differences - if you switch off the current, the magnetic field is lost, and the strength of the magnetic field can be altered by either changing the number of coils around the core, or by changing the current. I intend to measure the strength of an electromagnet - a magnet consisting of an iron core with plastic-coated wire rapped around. When current is applied through the wire, the iron core becomes magnetic - and I intend to test the effect of varying the current. The factors that will have an affect on the quantity I'm investigating include room temperature, material of core, number of coils around the core - I intend to keep all of these constant. The factor I intend to vary in my investigation (independent variable) will be current - the current flowing through the coils of the electromagnet. I have chosen this as I think it will be the easiest to investigate and carry out. The other variables (number of coils) will be kept constant so as to give valuable and worthwhile results. Prediction My prediction is that the amount of current passed
The Compact Disc.
The Compact Disc The compact disc if by far one of the most revolutionary mediums to have been invented in recent times. It has completely changed society in a numbers of ways and has benefited everyone. In this coursework I aim to discover how a CD is produced, written on and how it is read inside a CD-ROM. I will also be looking at the difference between a CD-R and a CD-RW. The average CD-R or RW can hold about 6 billion bits of binary data. This is about 780 megabytes of data, and at 2000 characters per page an average CD can store up to 275,000 pages of text. A CD can also hold about 74 minutes of audible music as it samples at 44.1kHz. The first aspect I chose to look at was how a CD is produced at a manufacturing plant and what materials and components go into making a CD. A CD is made up of a number of components. Its base material is polycarbonate; it is what makes the CD strong and provides a surface for other layers to be applied to. A reflective layer is then applied to the surface of the polycarbonate using a process called sputtering. This is a shiny layer that is used to bounce the laser beam back to its original source. This means that this layer must have a very high integrity so that it remains in shape and not break apart. This reflective layer is usually made up of silver, but on occasions it is made up of gold or platinum. With a CD-R and CD-RW there is
What factors affect the strength of electromagnetism?
Physics Coursework What factors affect the strength of electromagnetism? Planning Introduction A home made magnet is essentially a metal core, with a wire coiled around it. The core should be a 'soft' metal, for example soft iron. A 'soft' metal is one that is easily magnetised and demagnetised, and a 'soft' iron core increases the field strength. A wire coil that carries current is called a solenoid, and this solenoid is wound around the soft iron core. When a current is passed through the circuit, and the coil, a magnetic field is produced at the centre. This aligns the particles in the iron core, which are tiny magnetic domains pointing in all directions in the absence of current, in one direction. A magnetic field is produced around the electromagnet - a magnetic field is a region where magnetic materials (e.g. iron and steel) and also wires carrying a current experience a force acting on them. Magnetism is said to be induced in the soft iron core, that is, the soft iron core becomes magnetised. It is electricity through the coil and the magnetism that it induces in the iron core, which give it the name electromagnet. I used the book "Physics for You" by Keith Johnson. De-magnetised metal Magnetised Metal Factors There are numerous factors but I will talk about the three main factors. * The number of turns on the coil * The current through the coil * Material
The Benefits and repercussions of the use of mobile phones in a third world country: El Salvador
The Benefits and repercussions of the use of mobile phones in a third world country: El Salvador Introduction The widespread of the use of mobile phones in El Salvador is a very recent phenomenon, dating itself from its growth in the year 1997. Their use has increased in the past decade. Now making them an indispensable tool in business, commerce and for regular society too. From recent studies, it has been deduced that by April 2001, there were approximately three to three million and a half of mobile phones in circulation in the country. This in an equivalent of one phone for every 3 people. Two of the main companies providing the service are from Telefonica (MoviStar) and Telemovil de El Salvador. The extensive use of this device had leaded not only in the country but also worldwide the concern and public debate about the effects on human health. The concern focuses deeply in the context of the emissions of radio frequency radiation (RF) from both the mobile phone itself and the base station that provides the signal to the device. The levels of exposure increase from the handset itself if it is held near to the head or other parts of the body, rather than exposing the whole body to the frequencies of the base station. There are two main ways by which the health is directly jeopardized by the RF radiation. These are by thermal effects caused mainly by holding the mobile
Physics in the real world - During my visit to Broomfield Hospital I witnessed two aspects of physics in every day use. These were X-Rays and ultrasound; they both do similar jobs, although they both have limitations.
Physics in the real world During my visit to Broomfield Hospital I witnessed two aspects of physics in every day use. These were X-Rays and ultrasound; they both do similar jobs, although they both have limitations. A German physicist named Wilhelm Roentgen first discovered X-Rays in 1895, the discovery of X-Rays revolutionised medical science, and it allowed doctors to see through human tissue, to examine broken bones, swallowed objects, and with a modified version, to examine tissues such as the lungs. They can be used to study the softer tissue of the body, they do this by introducing "contrast media" into the body, this is often a barium compound. If the doctor wants to examine the blood vessels it will be injected into the blood stream. X-Rays can also be recorded as a moving image by a process called fluoroscopy, in which the X-Rays pass through the body onto a fluorescent screen, creating a moving X-Ray image, which can then be recorded onto a film. X-Rays are not only used in the medical world, they are also used in airport security, to scan your bags. They are also used to detect flaws in big castings, to study quantum mechanics, crystallography and cosmology. The only problem with X-rays Is that they are a form of ionising radiation, which means that when it hits an atom, it can knock an electron off, turning the atom into a ion. Ions can then collide with more
Effect of Underwater Acoustics on Whales.
Effect of Underwater Acoustics on Whales Biology 220W Leah Kim Student ID # 207740335 Section# 001 Abstract: Whales utilize acoustic frequencies to communicate underwater. If the whales are unable to communicate their bi-annual migration can become perilous. Man-made low frequency sonar can prevent whales from producing sound and sometimes causes them to take alternate routes. When the whales try to avoid the sonar they are in danger of running ashore and perishing after being beached. Introduction: Twice a year, around the months of December and May, populations of gray whales migrate from Mexico to Alaska. (Unknown1, 2002) During this journey, they pass the state of California, where acoustical pulses, generated by air guns or water guns, are used in seismic surveys. If the seismic-generated sound waves exceed the "background" noise or normal amount of noise, they could interfere with gray whale communication or disturb behavior. (Unknown1, 2002) It is possible that seismic surveys have a detrimental impact on marine life, such as gray whales. Whales are able to perceive sound in a wide range of frequencies from 75 Hz up to 150 Hz. In experimental conditions, where the environment's level of noise is controlled, the whales are more sensitive and hear from 10 Hz to 100 Hz. In addition, smaller whales have a broader range from which they can hear from 10 up
An Investigation Into the Effect of Wave Exposure on the Volume of Limpets
An Investigation Into the Effect of Wave Exposure on the Volume of Limpets Abstract: The aim of this investigation was to explore the effect of wave exposure on the volumes of intertidal limpets. Samples of the Patella spp. were measured at 2 different sites at West Angle Bay. A 0.25m2 quadrat was used to measure along a continuous horizontal belt transect at a fixed vertical height and the base diameter and vertical height of each limpet was measured using callipers. These measurements were then used to calculate the volumes of each limpet. The results obtained showed a measurable difference in the volumes obtained at the exposed shore site compared with the sheltered shore site. The results showed that there was a higher frequency of smaller limpets and a lower frequency of larger limpets at the wave-exposed site than at the sheltered site. Therefore wave exposure has a profound effect on the size distribution of this intertidal limpet species. The reasons for this are that the effects of wave action are more at the exposed shore site. As a result of the force of the water's acceleration increasing at a faster rate than the organisms ability to hold on as an organism grows, wave exposure prevents the distribution of larger limpets. When limpets are mobile their adhesive tenacity is much less than when they are stationary. This suggests that due to their reduced
